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INA180: Putting Unidirectional supply in bidirectional situation

Prodigy 60 points

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Part Number: INA180

I would like to use an INA180 in low side configuration to measure the charge current of a battery (shunt lives on the negative terminal of the battery).   However, there are situations where the battery will be discharging. I don't care about measuring the discharge current in this situation but I want to make sure I will not damage the INA180 device or cause extra unwanted current draw in this situation where IN+ has a lower voltage than IN-.

At full scale discharge, IN+ would have the lowest voltage of the system - but it would be well above the -0.2V Minimum common mode input voltage spec.

Is the INA180 device okay in this condition? I would expect it to output the lowest voltage it can output (close to the 0V rail) but not damage the device.

  • Hi Daniel,

    As long as the minimum input common-mode voltage of -0.2V is being met, the INA180 will be fine. If the differential input voltage is negative, the input stage will be cutoff and the output stage will output the lowest possible voltage, roughly 20mV above GND. This will not damage the part.

    If Vcm goes below -0.3V, you risk turning on the input ESD cells and conducting high currents through the device, which could lead to damage. If that is a possibility, then I advice using external protection components or adjusting your design.

    Best regards,

    Ian Williams
    Applications Manager
    Current & Magnetic Sensing

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